随机数

在产生测试数据时，很有用

create table test_date
(
id number(8),
create_date date,
username varchar2(20),
address varchar2(40)
);

declare
begin
for i in 1..1000000 loop
insert into test_date values(test_date_id.nextval, sysdate+i/(1440*60), dbms_random.string('a',8) ,dbms_random.string('a',20));
if mod(i,10000)=0 then
commit;
end if;
END loop;
end;

记录一下语法：
opt
Specifies what the returning string looks like:

'u', 'U' - returning string in uppercase alpha characters

'l', 'L' - returning string in lowercase alpha characters

'a', 'A' - returning string in mixed case alpha characters

'x', 'X' - returning string in uppercase alpha-numeric characters

'p', 'P' - returning string in any printable characters.

Otherwise the returning string is in uppercase alpha characters.

len
The length of the returning string.